Black-handed Spider Monkey

Geoffroy's spider monkey is a large New World monkey found across much of Central America and parts of Mexico, living in rainforest, semideciduous and mangrove forests. It is arboreal and active by day, mostly in the upper forest, and travels by swinging beneath branches on long arms and hook-like hands with only a vestigial thumb. Its strong prehensile tail works as an extra limb and can bear the monkey's full weight. Groups of 20 to 42 split into smaller subgroups to forage over large tracts of forest, and the diet is mostly ripe, fleshy fruit supplemented by leaves, flowers, bark, insects and honey. Water is often drunk from tree holes and bromeliads.

About the black-handed spider monkey

The black-handed spider monkey is also known as Geoffroy's spider monkey or the Central American spider monkey, and it's one of the largest New World monkeys, sometimes weighing as much as 9 kg (20 lb). It belongs to the family Atelidae, which also holds the woolly monkeys, muriquis, and howler monkeys, and it sits in the genus Ateles alongside every other spider monkey species. The genus name itself means "imperfect," a nod to the vestigial thumb that barely shows on its hands. At least five subspecies are recognized, sorted mostly by fur color and geography, and some researchers group the black-headed spider monkey of Panama, Colombia, and Ecuador in with this species as well.

Body color shifts by subspecies and population — buff, reddish, rust, brown, or black — but the hands and feet are consistently dark or black, which is where the common name comes from. The face usually carries a pale mask with bare skin around the eyes and muzzle. The arms are about 25% longer than the legs and end in long, strong, hook-like fingers built for swinging rather than gripping small objects; the thumb barely functions at all. The real engineering marvel is the tail: prehensile, strong, and tipped with a palm-like pad, it acts as a fifth limb. A black-handed spider monkey can hang its entire body weight from its tail alone, which frees both hands to pick fruit or scoop water out of a tree hollow.

In the wild, this monkey ranges through Panama, Costa Rica, Nicaragua, Guatemala, Honduras, El Salvador, Belize, and the southern and eastern portions of Mexico, with local reports suggesting a small population may extend into Colombia near the Panama border. It lives in rainforest, semideciduous forest, and mangrove forest, and tends to turn up in higher densities where the forest is evergreen. Because it needs large, connected tracts of trees to move, feed, and find mates, it disappears quickly from any area where forest cover is broken up.

Behavior and diet

Black-handed spider monkeys are arboreal and diurnal, spending most of their time in the upper canopy, though they come down to the ground more often than other spider monkey species. They live in fission-fusion societies — a loose community of 20 to 42 members that splits into smaller subgroups of two to six animals to forage during the day, sometimes staying apart even overnight. These groups can range across more than 900 hectares (2,200 acres) of forest, and an individual monkey may cover about 2,000 meters (6,600 ft) in a single day. Males and dominant individuals tend to travel the farthest.

Movement is the most distinctive part of its behavior. It brachiates — swings arm over arm beneath branches, tail assisting — more than it walks, and it crosses gaps between trees mainly by "bridging," reaching for a branch in the next tree and pulling it close enough to climb across. When it isn't moving, it often hangs rather than sits, suspended by the tail alone or by the tail and one or more limbs together. The diet is dominated by ripe, fleshy fruit, which takes up 70–80% of feeding time; young leaves fill out most of the rest, supplying protein that fruit lacks, and the monkey also eats flowers, bark, insects, honey, seeds, and buds. Fruit and leaves supply most of its water too, though unlike other spider monkeys it will also drink from water sources on the ground.

Communication runs through barks, whinnies, squeals, squeaks, and screams, each animal with its own distinctive voice. Barks signal alarm; whinnies call the group to food or keep members in contact while traveling. Females give birth roughly every two to four years after a gestation of about 7.5 months, typically to one infant that rides on the mother's chest and later her back, nursing for about a year while beginning to eat solid food and move on its own around three months old. Females leave their birth group at sexual maturity, around age four, while males stay, which is why males within a group tend to be related.

Range and habitat

The black-handed spider monkey's range covers much of Central America — Panama, Costa Rica, Nicaragua, Guatemala, Honduras, El Salvador, and Belize — along with the southern and much of the eastern portion of Mexico. Local observations suggest the southernmost subspecies may also reach into a corner of Colombia near the Panama border, though in western Colombia and northeastern Panama it's replaced by the closely related black-headed spider monkey.

It occupies several forest types: rainforest, semideciduous forest, and mangrove forest, with the highest population densities generally found where evergreen forest still stands. Because the species requires large, unbroken tracts of forest to sustain its wide-ranging foraging groups, it has vanished from areas where that forest has been cleared or fragmented, even where some tree cover remains.

Conservation status

The black-handed spider monkey is listed as Endangered, driven mainly by habitat loss and by capture for the pet trade; hunting adds further pressure in some areas. Its low reproductive rate — females typically produce one offspring every two to four years — means populations recover slowly once numbers drop, and the species has already disappeared from parts of its former range. One subspecies is classified as endangered and two others as critically endangered.

On Barro Colorado Island in Panama, hunting wiped out the native population by 1912. A reintroduction effort between 1959 and 1966 released at least 18 monkeys, of which only five survived — one male and four females. That small founding group grew into a population of 28 monkeys by 2003.